Solvent absorbing device and image forming apparatus

ABSTRACT

The solvent absorbing device includes: a hollow open roller composed of a cylindrical member of which inner side is divided into at least a first space and a second space in such a manner that a cross-section of the cylindrical member in a plane perpendicular to an axial direction of the cylindrical member is divided into a plurality of regions, the cylindrical member having a first opening section and a second opening section passing from an outer surface of the cylindrical member to an inner surface of the cylindrical member and opening respectively to the first space and the second space; a cylindrical absorbing body which is arranged over the outer surface of the cylindrical member and is rotatable in a rotational direction relatively to the hollow open roller; and a pressure application device which applies a negative pressure to the first space of the hollow open roller, and applies a prescribed pressure to the second space of the hollow open roller. The first and second opening sections are disposed other than a position facing a portion of a surface of the absorbing body making in contact with solvent, and the first opening section is disposed on an upstream side of the second opening section in terms of the rotational direction of the absorbing body.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a solvent absorbing device and to an image forming apparatus, and more particularly, to a solvent absorbing device and an image forming apparatus whereby excess solvent on a medium is collected by rotating a cylindrical absorbing body.

2. Description of the Related Art

In general, an inkjet recording apparatus performs recording by ejecting ink droplets toward a recording medium from a plurality of nozzles, which are formed in a recording head (inkjet head). The inkjet recording apparatus is widely used due to its excellence low-noise performance, low running costs, and the fact that it is capable of recording images of high quality onto recording media of various different types. The ink ejection methods include, for example, a piezoelectric method, which uses the displacement of a piezoelectric element, a thermal method, which uses thermal energy generated by a heating element, and the like.

In the inkjet recording apparatus, an ink of relatively low viscosity is used due to the ejection system, and it is then necessary to remove the excess solvent (generally, water or the like) from the recording medium on which the ink has been deposited. If the excess solvent is not removed sufficiently, then problems are liable to occur, such as bleeding of the recorded image, wrinkling of the recording medium, and the like. In particular, when using a non-permeable medium (for example, plastic, metal, glass, or the like) as the recording medium, bleeding is liable to occur in the recorded image, and this may cause deterioration of image quality.

There is an inkjet recording apparatus based on an intermediate transfer method, in which an image is formed on an intermediate transfer body by depositing ink from a recording head and the image is then transferred to a recording medium. Even in the recording apparatus of this kind, there is a problem in that a satisfactory transferred image cannot be obtained unless the excess solvent on the intermediate transfer body is removed satisfactorily.

There is an inkjet recording apparatus based on a two-liquid reaction method, which uses an ink and a treatment liquid causing an aggregating reaction of the coloring material in the ink, and mixes and causes the reaction of the ink and the treatment liquid on the medium (the recording medium or the intermediate transfer body). In the inkjet recording apparatus based on the two-liquid reaction method particular, since a large amount of solvent is deposited on the surface of the medium, then the aforementioned problems caused by the excess solvent are even more liable to occur.

In order to resolve the above-described problems, various technologies have been proposed thus far in order to remove excess solvent from the surface of the medium, such as the recording medium or the intermediate transfer body (see, for example, Japanese Patent Application Publication Nos. 2001-179959 and 2002-023504).

Japanese Patent Application Publication No. 2001-179959 discloses a liquid solvent absorbing body that absorbs liquid solvent through an ink absorbing body making contact with the ink. A ventilation device is provided inside the liquid solvent absorbing body, whereby the liquid solvent absorbed by the absorbing body can escape from the inner side of the body. However, this is problematic in that since the air flows into the absorbing body from all sides, then the suction force is low and it is difficult to collect the excess solvent, unless the surface of the absorbing body is sealed with liquid, or the like.

Japanese Patent Application Publication No. 2002-023504 discloses a liquid removal apparatus that collects a development solution. This liquid removal apparatus has a porous cylinder and a shielding body, which is not permeable to air and arranged at a position inside the porous cylinder where it makes contact with the liquid, and the liquid is collected by reducing the pressure inside the porous cylinder. However, although this resolves the problems associated with Japanese Patent Application Publication No. 2001-179959, since it is only able to suction from a part of the porous body, then while it is possible to collect the excess solvent, it is not possible to dry the porous body sufficiently. If the porous body is not dried sufficiently, then the absorption performance of the porous body is reduced, and the excess solvent cannot be collected adequately.

SUMMARY OF THE INVENTION

The present invention has been contrived in view of these circumstances, an object thereof being to provide a solvent absorbing device and an image forming apparatus whereby there is no decline in the excess solvent absorption performance and excess solvent can be collected reliably.

In order to attain the aforementioned object, the present invention is directed to a solvent absorbing device, comprising: a hollow open roller composed of a cylindrical member of which inner side is divided into at least a first space and a second space in such a manner that a cross-section of the cylindrical member in a plane perpendicular to an axial direction of the cylindrical member is divided into a plurality of regions, the cylindrical member having a first opening section and a second opening section passing from an outer surface of the cylindrical member to an inner surface of the cylindrical member and opening respectively to the first space and the second space; a cylindrical absorbing body which is arranged over the outer surface of the cylindrical member and is rotatable in a rotational direction relatively to the hollow open roller; and a pressure application device which applies a negative pressure to the first space of the hollow open roller, and applies a prescribed pressure to the second space of the hollow open roller, wherein the first and second opening sections are disposed other than a position facing a portion of a surface of the absorbing body making in contact with solvent, and the first opening section is disposed on an upstream side of the second opening section in terms of the rotational direction of the absorbing body.

According to this aspect of the present invention, it is possible to promote the collection of the excess solvent by the absorbing body through the first opening section corresponding to the first space, due to the negative pressure applied to the first space, as well as being able to dry the absorbing body through the second opening section corresponding to the second space, at the downstream side in terms of the rotational direction of the absorbing body, due to the prescribed pressure applied to the second space. In other words, in the absorbing body rotating over the outer side of the hollow open roller, the solvent collection and the drying are repeated alternately, and consequently there is no decline in the absorptive properties of the absorbing body and it is possible to collect the excess solvent continuously in a reliable manner, while maintaining a prescribed absorption performance.

Preferably, the pressure application device applies a negative pressure to the second space.

According to this aspect of the present invention, it is possible to collect the excess solvent contained in the absorbing body reliably to the inner side (the side of the second space), without the excess solvent being expelled to the outer side, and therefore the absorbing body can be dried in a reliable manner.

It is also preferable that the pressure application device applies a positive pressure to the second space.

According to this aspect of the present invention, since foreign material adhering to the surface of the absorbing body can be blow out from the inner side toward the outer side, as well as the excess solvent contained in the absorbing body, then it is possible to prevent blockages as well as drying the absorbing body.

Preferably, the solvent absorbing device further comprises a heating device which heats air to be supplied to the second space.

According to this aspect of the present invention, it is possible to promote the evaporation of the excess solvent contained in the absorbing body, as well as being able to lower the viscosity of the excess solvent, and therefore the excess solvent can be blown out readily to the outer side of the absorbing body and the absorbing body can be dried in a more reliable fashion.

Preferably, the cylindrical member further has a third space in the inner side and a third opening section opening to the third space; the third opening section is disposed on a downstream side of the first opening section and the upstream side of the second opening section in terms of the rotational direction of the absorbing body; and the solvent absorbing device further comprises a liquid deposition device which deposits a prescribed liquid onto the surface of the absorbing body and is arranged at a position facing the third opening section through the absorbing body.

According to this aspect of the present invention, the liquid deposited on the surface of the absorbing body by the liquid deposition device is absorbed into the absorbing body by means of the third opening section corresponding to the third space, due to the negative pressure applied to the third space, and therefore it is possible to lower the viscosity of the excess solvent contained in the absorbing body. Consequently, the absorbing body can be dried in a more reliable fashion, to the downstream side in terms of the direction of rotation of the absorbing body.

If a cleaning liquid is deposited by the liquid deposition device, then it is possible to remove foreign matter adhered to the absorbing body, as well as being able to prevent blockages.

Preferably, the cylindrical member further has a liquid storage section in the inner side, collected excess solvent being accumulated in the liquid storage section.

According to this aspect of the present invention, since there is no need to provide a separate container for storing the excess solvent that has been collected, then space savings can be made.

In order to attain the aforementioned object, the present invention is also directed to an image forming apparatus comprising the above-described solvent absorbing device.

According to the present invention, it is possible to promote the collection of the excess solvent by the absorbing body through the first opening section corresponding to the first space, due to the negative pressure applied to the first space, as well as being able to dry the absorbing body through the second opening section corresponding to the second space, at the downstream side in terms of the rotational direction of the absorbing body, due to the prescribed pressure applied to the second space. In other words, in the absorbing body rotating over the outer side of the hollow open roller, the solvent collection and the drying are repeated alternately, and consequently there is no decline in the absorptive properties of the absorbing body and it is possible to collect the excess solvent continuously in a reliable manner, while maintaining a prescribed absorption performance.

BRIEF DESCRIPTION OF THE DRAWINGS

The nature of this invention, as well as other objects and advantages thereof, will be explained in the following with reference to the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures and wherein:

FIG. 1 is a schematic drawing showing a composition of an inkjet recording apparatus according to an embodiment of the present invention;

FIG. 2 is a principal block diagram showing a system configuration of the inkjet recording apparatus;

FIGS. 3A and 3B are schematic drawings showing compositions of inkjet recording apparatuses according to embodiments of the present invention;

FIG. 4 is a schematic drawing showing a composition of a solvent absorbing device according to a first embodiment;

FIGS. 5A and 5B are external perspective diagrams including partial cross-sections showing compositions of solvent absorbing rollers;

FIG. 6 is a schematic drawing showing a composition of a solvent absorbing device according to a second embodiment;

FIG. 7 is a schematic drawing showing a composition of a solvent absorbing device according to a third embodiment;

FIG. 8 is a schematic drawing showing a composition of another solvent absorbing device according to the third embodiment;

FIG. 9 is a schematic drawing showing a composition of a solvent absorbing device according to a fourth embodiment;

FIG. 10 is a schematic drawing showing a composition of another solvent absorbing device according to the fourth embodiment;

FIG. 11 is a schematic drawing showing a composition of yet another solvent absorbing device according to the fourth embodiment;

FIG. 12 is a schematic drawing showing a composition of a solvent absorbing device according to a fifth embodiment; and

FIG. 13 is a schematic drawing showing a composition of a solvent absorbing device according to a sixth embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Image Forming Apparatus

FIG. 1 is a schematic drawing showing a composition of an inkjet recording apparatus according to an embodiment of an image forming apparatus relating to the present invention.

The inkjet recording apparatus 10 shown in FIG. 1 is based on an intermediate transfer method, in which an image is formed on an endless belt-shaped intermediate transfer body 12 and the image is then transferred to a recording medium 14. The intermediate transfer body 12 is made of a non-permeable material (for example, a polyimide film, urethane rubber, silicone rubber, or the like). It is also possible to make only the layer on the outer surface of the intermediate transfer body 12 (the side on which the ink is deposited), from a non-permeable material.

In FIG. 1, the intermediate transfer body 12 is configured to be wound about the exterior of three rollers 16, 18 and 20. The first roller 16 is a drive roller, to which the motive force of a drive motor 48 (see FIG. 2) is transmitted, and the second roller 18 and the third roller 20 are idle rollers, which rotate due to the movement of the intermediate transfer body 12. When the first roller 16 rotates due to the driving of the drive motor 48, the intermediate transfer body 12 turns in the counter-clockwise direction in FIG. 1 (hereinafter, called the “direction of rotation of the transfer body”) due to the rotation of the first roller 16.

A plurality of recording heads 22 (22K, 22C, 22M and 22Y), which correspond to colored inks of black (K), cyan (C), magenta (M) and yellow (Y), respectively, are arranged in sequence from the upstream side in the direction of rotation of the transfer body, at positions facing the outer circumferential surface of the intermediate transfer body 12, between the first roller 16 and the second roller 18.

The recording heads 22 (22K, 22C, 22M and 22Y) are configured as long full-line heads, in each of which a plurality of nozzles are arranged through the maximum recordable width in the breadthways direction of the intermediate transfer body 12 (the direction perpendicular to the direction of rotation of the transfer body; the direction of the lo obverse-reverse of the sheet containing FIG. 1). The colored irks (K, C, M, Y) are ejected as droplets from the corresponding nozzles.

It is possible to record an image on the whole surface of the intermediate transfer body 12 by means of just one operation of relatively moving the intermediate transfer body 12 and the recording heads 22 with respect to each other, in the direction of rotation of the transfer body, without moving the recording heads 22 in the breadthways direction of the intermediate transfer body 12. Therefore, the recording speed can be raised. Higher-speed printing is thereby made possible and productivity can be improved in comparison with a shuttle type head configuration, in which a recording head reciprocates in the direction orthogonal to the paper conveyance direction (the main scanning direction).

Of course, the present invention can also be applied to a serial type of recording apparatus, which records an image on an intermediate transfer body 12 while moving a recording head of short dimensions (a serial head) reciprocally in the breadthways direction of the intermediate transfer body 12.

The ejection method of the recording heads 22 uses a piezoelectric method whereby droplets of the inks are ejected from the nozzles by pressurizing the inks inside the pressure chambers by utilizing the displacement of piezoelectric elements, or a thermal method whereby bubbles are generated in the inks inside pressure chambers (also called bubble chambers) by using the thermal energy created by heating elements, and droplets of the inks are ejected from the nozzles due to the pressure caused by the growth of the bubbles. Other types of ejection methods may also be used.

A platen 24 serving as a supporting member for the intermediate transfer body 12 is disposed at a position facing the recording heads 22 across the intermediate transfer body 12.

The droplets of the inks are ejected from the recording heads 22 in a state where at least the portion of the surface of the intermediate transfer body 12 that opposes the recording heads 22 is kept flat by the platen 24.

A solvent removing roller 50 to which the present invention is applied is disposed on the downstream side from the recording head 22Y in terms of the direction of rotation of the transfer body, in such a manner that the solvent removing roller 50 substantially makes contact with the outer surface of the intermediate transfer body 12. The solvent removing roller 50 is a solvent removal device, which removes excess solvent by making contact with the solvent of the inks that have been deposited on the intermediate transfer body 12. The concrete composition of the solvent removing roller 50 is described in detail hereinafter.

In the embodiment shown in FIG. 1, one solvent removing roller 50 is arranged on the firthest downstream side of the recording heads 22; however, the implementation of the present invention is not limited to this. For instance, there is also a mode in which solvent removing rollers 50 are disposed respectively on the downstream sides of the recording heads 22. This mode is especially suitable for cases where the amount of solvent of the inks deposited by the recording heads 22 is high, and it enables the excess solvent to be collected reliably.

A transfer unit 26, which transfers the image from the intermediate transfer body 12 to the recording medium 14, is disposed on the downstream side of the solvent removing roller 50 in terms of the direction of rotation of the transfer body. A nip roller 28 is arranged in the transfer unit 26 at a position facing the third roller 20 across the intermediate transfer body 12, and a prescribed nip pressure is applied by the nip roller 28 to the inner surface side of the recording medium 14 (the surface reverse to the recording surface)

Next, the action of the inkjet recording apparatus 10 is described.

Firstly, the ink droplets are ejected from the recording heads 22 (22K, 22C, 22M and 22Y) and deposited on the intermediate transfer body 12, thereby forming an image on the intermediate transfer body 12. When the image forming region (the region where the ink droplets have been deposited) on the intermediate transfer body 12 is moved to the position where the solvent removing roller 50 is disposed, on the downstream side in terms of the direction of rotation of the transfer body, then the excess solvent of the inks on the intermediate transfer body 12 is removed by the solvent removing roller 50. Moreover, when the image forming region on the intermediate transfer body 12 from which the excess solvent has been removed is then moved to the transfer unit 26, which is on the downstream side, then the image is transferred from the intermediate transfer body 12 to the recording medium 14, while the prescribed nip pressure is applied by the nip roller 28, to the inner surface side of the recording medium 14. Thereupon, the recording medium 14 onto which the image has been transferred is outputted to the exterior of the inkjet recording apparatus 10.

Although the configuration with the KCMY four standard colors is described in the present embodiment, combinations of the colored inks and the number of colors are not limited to those. Light colored inks, dark colored inks or special colored inks can be added as required. For example, a configuration is possible in which recording heads for ejecting light-colored inks such as light cyan and light magenta are added.

Although not shown in the drawings, there is a mode in which a treatment liquid deposition device, which deposits, onto the intermediate transfer body 12, a treatment liquid (coloring material aggregating liquid) containing a component that causes the coloring materials of the colored inks to aggregate, is disposed on the upstream side or the downstream side of the recording heads (ink ejection heads) 22 corresponding to the colored inks. The treatment liquid deposition device may adopt a mode using a recording head that ejects the treatment liquid (treatment liquid head) or a treatment liquid application roller, or the like. It is possible to provide either only one treatment liquid deposition device, or to provide a treatment liquid deposition device for each of the recording heads 22 corresponding to the colored inks. According to a mode which uses the treatment liquid in this way, the colored inks and the treatment liquid are deposited onto the intermediate transfer body 12, and an aggregate of the coloring materials is generated by the mixing and reacting of the colored inks and the treatment liquid on the intermediate transfer body 12. Therefore, it is possible to improve the fixing properties of the recorded image on the intermediate transfer body 12.

FIG. 2 is a principal block diagram showing the system configuration of the inkjet recording apparatus 10 of the present embodiment. As shown FIG. 2, the inkjet recording apparatus 10 includes a communication interface 30, a system controller 32, an image memory 34, a motor driver 36, a heater driver 3 8, a pressure driver 39, a print controller 40, an image buffer memory 42, a head driver 44, a print determination unit 47, and the like.

The communication interface 30 is an interface unit for receiving image data sent from a host computer 46. A serial interface or a parallel interface may be used as the communication interface 30. A buffer memory (not shown) may be mounted in this portion in order to increase the communication speed.

The image data sent from the host computer 46 is received by the inkjet recording apparatus 10 through the communication interface 30, and is temporarily stored in the image memory 34. The image memory 34 is a storage device for temporarily storing image data inputted through the communication interface 30, and the data is written and read to and from the image memory 34 through the system controller 32. The image memory 34 is not limited to a memory composed of semiconductor elements, and a hard disk drive or another magnetic medium may he used.

The system controller 32 is a control unit which controls the respective sections, such as the communication interface 30, the image memory 34, the motor driver 36, the heater driver 38, the pressure driver 39, and the like. The system controller 32 includes a central processing unit (CPU) and peripheral circuits thereof controls communications with the host computer 46 and reading from and writing to the image memory 34, and the like, and generates control signals for controlling the motors 48 and heaters 49 in the conveyance system.

The motor driver (drive circuit) 36 drives the motor 48 in accordance with commands from the system controller 32. The heater driver (drive circuit) 38 drives each heater 49 of the respective units in accordance with commands from the system controller 32.

In particular, in the inkjet recording apparatus 10 according to the present embodiment, the system controller 32 includes a pressure control unit 32a, by which the pressure apparatus 41 is controlled through a pressure driver 39. The pressure apparatus 41 corresponds to suction devices 74 and 76 (see FIG. 4) and a device 82 (see FIG. 7), which are described hereinafter. Furthermore, although not shown in the drawings, in the case of a mode where a heater 86 (see FIG. 9) is provided in the solvent absorbing device, which is described hereinafter, the system controller 32 also controls the heater 86.

The print controller 40 has a signal processing function for performing various tasks, compensations, and other types of processing for generating print control signals from the image data stored in the image memory 34 in accordance with commands from the system controller 32 so as to supply the generated print control signal (dot data) to the head driver 44. Prescribed signal processing is carried out in the print controller 40, and the ejection amount and the ejection timing of the ink droplets from the recording heads 22 are controlled through the head driver 44, on the basis of the print data. By this means, prescribed dot size and dot positions can be achieved.

The print controller 40 is provided with the image buffer memory 42; and image data, parameters, and other data are temporarily stored in the image buffer memory 42 when image data is processed in the print controller 40. The aspect shown in FIG. 2 is one in which the image buffer memory 42 accompanies the print controller 40; however, the image memory 34 may also serve as the image buffer memory 42. Also possible is an aspect in which the print controller 40 and the system controller 32 are integrated to form a single processor.

The head driver 44 generates drive signals for driving the actuators (e.g., piezoelectric elements) of the recording heads 22 on the basis of the print data supplied by the print controller 40, and the head driver 44 supplies the drive signals thus generated to the actuators. The head driver 44 can be provided with a feedback control system for maintaining constant drive conditions for the print heads.

The print determination unit 47 is a block that includes the line sensor, reads the image printed on the recording head 22, determines the print conditions (presence of the ejection, variation in the dot formation, and the like) by performing desired signal processing, or the like, and provides the determination results of the print conditions to the print controller 40.

According to requirements, the print controller 40 makes various corrections with respect to the recording head 22 on the basis of information obtained from the print determination unit 47.

FIGS. 3A and 3B are schematic drawings showing compositions of the inkjet recording apparatus according to other embodiments of the present invention. In FIGS. 3A and 3B, the parts common or similar with those in FIG. 1 are denoted with the same reference numerals.

In the inkjet recording apparatus 10A shown in FIG. 3A, an intermediate transfer body 12A constituted of a drum-shaped member is used. At least the surface of the intermediate transfer body (drum-shaped member) 12A is formed of a non-permeable medium. For example, the intermediate transfer body 12A used is formed by coating the surface of a metal drum with a layer of a non-permeable medium (polyimide, polytetrafluoroethylene, or the like).

Recording heads 22 (22K, 22C, 22M, 22Y) are arranged at positions facing the surface of the intermediate transfer body 12A, and a solvent removing roller 50 is arranged on the downstream side of the recording head 22Y in the direction of rotation of the transfer body (the counter-clockwise direction in FIG. 3A). The solvent removing roller 50 is disposed so as to substantially make contact with the surface of the intermediate transfer body 12A, and the solvent removing roller removes excess solvent from the intermediate transfer body 12A.

Here, the action of the inkjet recording apparatus 10A is described.

Firstly, an image is formed on the intermediate transfer body 12A by ejection of droplets of the inks from the recording heads 22 (22K, 22C, 22M, 22Y) corresponding to the respective colored inks. When the image forming region on the intermediate transfer body 12A (the region where the ink droplets have been deposited) arrives at the position where the solvent removing roller 50 is disposed, on the downstream side in the direction of rotation of the transfer body, due to the rotation of the intermediate transfer body 12A in the direction of rotation of the transfer body (the counter-clockwise direction in FIG. 3A), then the excess solvent on the intermediate transfer body 12A is removed by the solvent removing roller 50. Moreover, in the transfer unit 26, which is disposed further to the downstream side, the image is transferred from the intermediate transfer body 1 2A to the recording medium 14, in a state where a prescribed nip pressure is applied by the nip roller 28 to the recording medium 14 that has entered in between the intermediate transfer body 12A and the nip roller 28. Thereupon, the recording medium 14 onto which the image has been transferred is outputted to the exterior of the inkjet recording apparatus 10A.

The inkjet recording apparatus 10B shown in FIG. 3B is a direct recording type of recording apparatus, which records directly onto a recording medium 14B, by performing ink ejection from the recording heads 22 (22K, 22C, 22M, 22Y) corresponding to the respective colored inks, onto the recording medium 14B. In the present embodiment, a non-permeable medium (made of plastic, metal, glass, or the like), or a recording medium having a slow speed of permeation (coated paper, or the like), is used as the recording medium 14B.

A conveyance belt 12B, which serves as the conveyance device for the recording medium 14B, is an endless belt wound about the exterior of three rollers 16B, 18B and 20B. The first roller 16B is a drive roller, the second roller 18B is an idle roller and the third roller 20B is a tensioning roller. The third roller (tensioning roller) 20B is movable in the vertical direction in FIG. 3B, in order to avoid slack, distortion, or the like, of the conveyance belt 12B. By this means, since a prescribed tension is applied to the conveyance belt 12B, then it is possible to convey the recording medium 14B in a stable state at all times.

When the recording medium 14B is supplied onto the conveyance belt 12B by a paper conveyance mechanism (not shown), then due to the movement (rotation) of the conveyance belt 12B caused by the rotation of The drive roller 16B, the recording medium 14B is conveyed successively to positions facing the respective recording heads 22, the corresponding inks are deposited onto the recording medium 14B from the respective recording heads 22, and at a further downstream position in the paper conveyance direction (the left to right direction in FIG. 3B), the excess solvent on the recording medium 14B is removed by the solvent removing roller 50. Thereupon, the recording medium 14B is outputted to the exterior of the inkjet recording apparatus 10B.

The intermediate transfer bodies 12 and 12A in FIGS. 1 and 3A and the recording medium 14B in FIG. 3B are not limited to being non-permeable bodies, and for example, if using an ink of low permeability that has a viscosity of 20 cP or above, then it is possible to use a permeable body made of porous rubber, or the like.

The embodiment shown in FIG. 1 is desirable for the general paper having a high permeation speed, since the coloring materials are transferred to the paper after removing the excess solvent, and deterioration of the image quality due to bleeding of the coloring materials, wrinkling of the paper, or the like, is avoided. The embodiment shown in FIG. 3A can be considered to be similar to FIG. 1; however, since the apparatus becomes larger in size and the related costs are higher, then the composition in FIG. 1 is preferable.

Solvent Absorbing Device

Next, the solvent absorbing devices according to embodiments of the present invention are described with respect to the solvent absorbing device that has the solvent removing roller 50 used in the above-described inkjet recording apparatuses in FIGS. 1, 3A and 3B.

First Embodiment

FIG. 4 is a schematic drawing showing the composition of the solvent absorbing device according to a first embodiment. In FIG. 4, numeral 50 denotes a solvent removing roller, 52 denotes a nonpermeable medium, 54 denotes ink and treatment liquid (coloring material aggregating reaction liquid), 56 denotes coloring material (colorant), and 58 denotes a solvent. The non-permeable medium 52 corresponds to the intermediate transfer body 12 (in FIG. 1) or 12A (in FIG. 3A) or the recording medium 14B (see FIG. 3B), which is used in the above-described inkjet recording apparatus. The coloring material 56 is formed by pigment particles or dye that has aggregated and formed particles. FIG. 4 shows a mode where, when the non-permeable medium 52 having the ink 54 deposited on the surface thereof is conveyed in the medium conveyance direction (the direction of an arrow A in FIG. 4), then a portion of the solvent 58 (the excess solvent) on the non-permeable medium 52 is removed by the solvent removing roller 50.

As shown in FIG. 4, the solvent removing roller 50 is composed of a hollow open roller 60 and a cylindrical absorbing body (porous body) 62. The hollow open roller 60 is constituted of a cylindrical member, of which the inner side is divided into two spaces (chambers) 66 and 68 whereby the cross-section in the direction perpendicular to the axial direction is divided into a plurality of regions, and in which opening sections 70 and 72 are formed in the respective spaces 66 and 68 so as to pass from the outer surface of the cylindrical member to the inner surface thereof. The cylindrical absorbing body 62 is arranged over the outer surface of the hollow open roller 60, and is rotatable relatively with respect to the hollow open roller 60.

The inner side of the hollow open roller 60 is divided into the two spaces 66 and 68 by means of a plate-shaped partition 64, which is parallel to the axial direction of the roller 60 (the obverse-reverse direction of the sheet containing FIG. 4), and the first space 66 is a sucking space, which promotes the collection of the solvent through the absorbing body 62, and the second space 68 is a drying space for drying the absorbing body 62.

The first opening section 70, which corresponds to the first space 66, and the second opening section 72, which corresponds to the second space 68, are formed in the hollow open roller 60. The first and second spaces 66 and 68 on the inner side of the hollow open roller 60 respectively connect through the first and second opening sections 70 and 72 with the absorbing body 62, which is disposed over the outer side of the hollow open roller 60.

FIGS. 5A and 5B are external oblique views including partial cross-sections showing the composition of the solvent removing roller 50 according to the present embodiment. It is possible that each of the opening sections 70 and 72, which are formed respectively in the spaces 66 and 68, is formed as one large opening 73A as shown in FIG. 5A, or as a plurality of small openings 73B as shown in FIG. 5B. The shapes of the openings constituting the opening sections 70 and 72 are not limited in particular to the examples shown in FIGS. 5A and 5B, and besides the rectangular shape or the circular shape, it is of course also possible to adopt an elliptical shape, or other polygonal shapes. Furthermore, the sizes and shapes of the openings of the opening sections 70 and 72 do not have to be uniform. For example, it is also possible to achieve reliable drying by setting a larger opening surface area in the central portion of the roller, where the ejection volume, or the amount of solvent, is greater, relatively to the end portions. The solvent removing roller 50 shown in FIG. 4 depicts the cross-sectional view with respect to FIG. 5A, for example.

In implementing the present invention, although there are no particular restrictions on the opening area of each of the opening sections 70 and 72 (if each is constituted of a plurality of openings, the opening area is the total area of the plurality of openings), it is desirable that each of the opening sections 70 and 72 has as broad as possible the opening area in relation to the corresponding one of the spaces 66 and 68, from the viewpoint of raising the efficiency of the collection of the excess solvent through the absorbing body 62, and the drying of the absorbing body 62. On the other hand, it is also necessary to ensure the rigidity of the hollow open roller 60. Hence, it is desirable that each of the opening sections 70 and 72 has an opening area of 40% to 80%, more desirably 50% to 70%, with respect to the surface area of the inner surface (before the opening sections 70 and 72 are formed) that makes contact with the corresponding one of the spaces 66 and 68 of the cylindrical member forming the base of the hollow open roller 60.

As shown in FIG. 4, the solvent removing roller 50 is disposed so as to be substantially in contact with the surface of the non-permeable medium 52. More specifically, the solvent removing roller 50 is disposed in such a manner that at least a portion of the surface of the absorbing body 62, which rotates over the outer side of the hollow open roller 60, makes contact with the solvent 58 of the ink 54 that has been deposited on the non-permeable medium 52. In this case, from the viewpoint of preventing degradation of the image, it is desirable that the solvent removing roller 50 is disposed in such a manner that a slight gap is formed between the surface of the absorbing body 62 and the non-permeable medium 52, in such a manner that the surface of the absorbing body 62 does not make contact with the coloring material 56 on the non-permeable medium 52. When the surface of the absorbing body 62 makes contact with the solvent 58, the solvent 58 is absorbed into the absorbing body 62 by the capillary action in the absorbing body 62.

The opening sections 70 and 72, which are formed in the hollow open roller 60, are disposed at the positions that do not face the solvent contacting surface of the absorbing body 62. The reason for this is that if the opening sections 70 and 72 were disposed at the positions facing the solvent contacting surface of the absorbing body 62, then due to the effects of the negative pressure applied to the spaces 66 and 68, as described hereinafter, the coloring material 56 would adhere to the surface of the absorbing body 62, giving rise to degradation of the image.

The first opening section 70 and the second opening section 72 are arranged successively on the downstream side in the direction of rotation of the absorbing body 62 (the direction of arrow B in FIG. 4), from the solvent contacting surface of the absorbing body 62. In other words, the first opening section 70 is disposed on the upstream side of the second opening section 72, in terms of the direction of rotation of the absorbing body 62.

Lets of the suction devices 74 and 76 are connected respectively to the spaces 66 and 68, and outlets of the suction devices 74 and 76 are connected to a common liquid collection container 78. The liquid collection container 78 is an unsealed container having an air connection hole 78 a formed in a portion thereof. Prescribed negative pressures (suction pressures) are applied to the spaces 66 and 68 by the suction devices 74 and 76. The negative pressures applied to the spaces 66 and 68 may be same or they may be different.

Due to the negative pressure applied to the first space 66, the negative pressure is transmitted to the peripheral area of the solvent contacting surface of the absorbing body 62 through the first opening section 70, and therefore the collection of the excess solvent through the absorbing body 62 can be promoted. Consequently, the first opening section 70 is desirably positioned in the vicinity of the solvent contacting surface of the absorbing body 62, to the downstream side thereof in terms of the direction of rotation of the absorbing body 62. For example, it is desirable that the lower end (the end on the side of the non-permeable medium 52) of the first opening section 70 is disposed at a position that is distanced at least 5 mm from the liquid surface of the solvent 58 on the non-permeable medium 52.

It is necessary that the negative pressure applied to the first space 66 is set to a suitable range. If the absolute value of the negative pressure applied to the first space 66 is too great (i.e., the pressure applied to the first space 66 is excessively less than the atmospheric pressure), then the negative pressure is transmitted to the non-permeable medium 52 through the first opening section 70 and the gap inside the absorbing body 62, and therefore it is possible that image degradation may occur due to the adherence of the coloring material 56 to the surface of the absorbing body 62. On the other hand, if the absolute value of the negative pressure applied to the first space 66 is too little (i.e., the pressure applied to the first space 66 is not enough less than the atmospheric pressure), then it is not possible sufficiently to collect the excess solvent from the non-permeable medium 52. Consequently, it is desirable that the negative pressure applied to the first space 66 is set to the appropriate range whereby the aforementioned problems can be prevented. Hereinafter, the expression “the negative pressure is great” means that the absolute value of the negative pressure is great and the pressure is relatively much less than the atmospheric pressure, and the expression “the negative pressure is little” means that the absolute value of the negative pressure is little and the pressure is not much less than the atmospheric pressure.

Due to the negative pressure applied to the second space 68, it is possible to dry the absorbing body 62 through the second opening section 72. When a great negative pressure is applied to the second space 68, since the interior of the absorbing body 62 that corresponds to the second space 68 does not fill with the solvent, then the negative pressure is not transmitted through the interior of the absorbing body 62 and air flows into the solvent removing roller 50 from outside. Consequently, it is possible to set the negative pressure applied to the second space 68 greater than the negative pressure applied to the first space 66, and it is thus possible to improve the drying capacity in relation to the absorbing body 62.

The negative pressures applied to the spaces 66 and 68 can be controlled by means of the suction forces of the suction devices 74 and 76, which are connected respectively to the spaces 66 and 68. The suction forces of the suction devices 74 and 76 can be controlled by changing the flow rates in the suction devices 74 and 76, for example.

For example, if the print rate (the print volume per unit surface area) is high and the amount of the excess solvent on the non-permeable medium 52 is large, then it is desirable to strengthen the suction forces of the suction devices 74 and 76, whereby the collection of the excess solvent through the absorbing body 62, and the drying of the absorbing body 62 can be further promoted. More specifically, the flow rates in the suction devices 74 and 76 are controlled in proportion with the print rate, as calculated from the image data.

Next, the operation start and halt timings of the suction devices 74 and 76 according to the present embodiment are described.

The operation start timing of the first suction device 74 is set between the start of the ink ejection by the recording heads 22 and the time at which the solvent 58 on the non-permeable medium 52 arrives at the absorbing body 62. Desirably, the amount of movement of the non-permeable medium 52 is measured by an encoder (not shown) or the like, and the operation of the first suction device 74 is started when the non-permeable medium 52 is at a position some 10 mm to 50 mm less than the distance of movement from the recording heads 22 to the absorbing body 62. Furthermore, the operation halt timing of the first suction device 74 is set to a time when the ink ejection by the recording heads 22 has ended and the solvent 58 is no longer present in the portion where the absorbing body 62 and the non-permeable medium 52 make contact. Desirably, the amount of movement of the non-permeable medium 52 from the end of the ink ejection by the recording heads 22 is measured by the encoder (not shown), and the operation of the first suction device 74 is halted when the non-permeable medium 52 is at a position some 10 mm to 50 mm greater than the distance of the movement from the recording heads 22 to the absorbing body 62.

On the other hand, the operation start timing of the second suction device 76 is set to the same timing as the operation start timing of the first suction device 74, and the operation halt timing of the second suction device 76 is set to the timing at which the non-permeable medium 52 halts.

Next, the action of the solvent absorbing device is described.

When a portion of the solvent 58 (the excess solvent) of the ink 54, that has been deposited on the non-permeable medium 52 makes contact with the absorbing body 62, which constitutes the surface of the solvent removing roller 50, then the excess solvent is absorbed into the absorbing body 62 due to the capillary action in the absorbing body 62. After absorbing the excess solvent, the portion of the absorbing body 62 containing the excess solvent moves to the position facing the first opening section 70, with the rotation of the absorbing body 62 in the direction of rotation of the absorbing body. In this case, since the negative pressure is applied on the first space 66 by the first suction device 74, then the excess solvent that has been absorbed in the absorbing body 62 is collected into the first space 66 through the first opening section 70, and is then collected into the collection container 78 through the suction device 74. After collecting the excess solvent, the portion of the absorbing body 62 containing the excess solvent moves to the position facing the second opening section 72, with the rotation of the absorbing body 62 in the direction of rotation of the absorbing body. Since the negative pressure is applied to the second space 68, the absorbing body 62 is dried through the second opening section 72. Subsequently, with the rotation of the absorbing body 62, the collection of the excess solvent by the absorbing body 62 and the drying of the absorbing body 62 are repeated alternately.

According to the present embodiment, since the prescribed negative pressures are applied respectively to the spaces 66 and 68, then it is possible to collect the excess solvent by means of the absorbing body 62 through the first opening section 70, and to dry the absorbing body 62 through the second opening section 72. Consequently, since the solvent collection and the drying are repeated alternately in the absorbing body 62 configured to be rotatable relatively with respect to the open hollow roller 60, then there is no decline in the absorptive properties of the absorbing body 62, and the collection of the excess solvent can be carried out continuously and reliably, while maintaining desired absorption performance.

In particular, in the present embodiment, since the suction devices 74 and 76 are connected respectively to the spaces 66 and 68, then by controlling the suction forces (for example, the flow rates) of the respective suction devices 74 and 76, it is possible to control independently the negative pressures applied to the spaces 66 and 68, and therefore the pressures can be optimized in accordance with the shapes of the first and second spaces 66 and 68, the first and second opening sections 70 and 72, and the shape and material of the absorbing body 62, and the like.

Second Embodiment

Next, a solvent absorbing device according to the second embodiment of the present invention is described. Below, the parts common with the first embodiment described above are not explained further, and the following description centers on the characteristic features of the second embodiment.

FIG. 6 is a schematic drawing showing the composition of the solvent absorbing device according to the second embodiment. In FIG. 6, the parts common or similar with those in FIG. 4 are denoted with the same reference numerals.

The solvent absorbing device shown in FIG. 6 has a check valve 80 arranged in the partition 64, which divides the interior of the hollow open roller 60 into the first and second spaces 66 and 68, and the suction device 74 is connected only to the first space 66. The check valve 80 is configured to be openable and closeable in accordance with the pressure difference between the first and second spaces 66 and 68, and when the check valve 80 is in the closed state, the first and second spaces 66 and 68 are not connected together, and when the check valve 80 is in the opened state, the first and second spaces 66 and 68 are connected together.

If the suction force of the suction device 74 is low and the negative pressure applied to the first space 66 is little, then the check valve 80 is in the closed state, and therefore the first and second spaces 66 and 68 are not connected and the absorption of the excess solvent by the absorbing body 62 is promoted through the first opening section 70.

On the other hand, if the suction force of the suction device 74 is high and the negative pressure applied to the first space 66 is great, then the check valve 80 is opened, and therefore the first and second spaces 66 and 68 are connected together. Consequently, the negative pressure in the first space 66 becomes less, the solvent absorbing force of the absorbing body 62 through the first opening section 70 is weakened, and the pressure in the second space 68 falls. Therefore, the absorbing body 62 is dried through the second opening section 72.

Similarly to the first embodiment, the operation start timing of the suction device 74 is set between the start of the ink ejection by the recording heads 22 and the time at which the solvent 58 on the non-permeable medium 52 arrives at the absorbing body 62. Desirably, the amount of movement of the non-permeable medium 52 is measured by an encoder (not shown) or the like, and the operation of the suction device 74 is started when the non-permeable medium 52 is at the position some 10 mm to 50 mm less than the distance of movement from the recording heads 22 to the absorbing body 62. Furthermore, the operational halt timing of the suction device 74 is simultaneous with the timing at which the non-permeable medium 52 halts.

According to the present embodiment, it is possible to promote the collection of the excess solvent by the absorbing body 62, as well as drying the absorbing body 62, simply by controlling the suction force of the suction device 74 connected to the first space 66, and therefore it is possible to achieve cost reductions as well as reducing the size of the apparatus (space savings). In particular, even in cases where there is a sudden change in the suction force of the suction device 74, it is still possible to maintain a uniform pressure in the first space 66 by means of the check valve 80, and therefore it is possible to prevent adherence of the coloring material 56 to the surface of the absorbing body 62.

Third Embodiment

Next, a solvent absorbing device according to the third embodiment of the present invention is described. Below, the parts common with the above-described embodiments are not explained further, and the following description centers on the characteristic features of the third embodiment.

FIG. 7 is a schematic drawing showing the composition of the solvent absorbing device according to the third embodiment. In FIG. 7, the parts common or similar with those in FIG. 4 are denoted with the same reference numerals.

In the solvent absorbing device shown in FIG. 7, the suction device 74 is connected to the first space 66 and a pressurization device 82 is connected to the second space 68. Since the negative pressure is applied to the first space 66 by the suction device 74, then it is possible to promote the collection of the excess solvent by the absorbing body 62 through the first opening section 70. On the other hand, since a positive pressure (i.e., a pressure higher than the atmospheric pressure) is applied to the second space 68 by the pressurization device 82, then it is possible to apply air flow to the absorbing body 62 through the second opening section 72 due to the air supplied to the second space 68, so as to blow away the solvent and foreign material inside the absorbing body 62 toward the outer side. Thus, it is possible to dry the absorbing body 62 while also preventing blockages. The operation start and halt timings of the suction device 74 are the same as in the first embodiment, and the operation start and halt timings of the pressurization device 82 are the same as the operation start and halt timings of the second suction device 76 in FIG. 4.

FIG. 8 is a schematic drawing showing another composition of the solvent absorbing device according to the third embodiment. In FIG. 8, the parts common or similar with those in FIG. 7 are denoted with the same reference numerals.

In the solvent absorbing device shown in FIG. 8, the liquid collection container 78 is a sealed container having a hermetically sealed interior, and the liquid collection container 78 and the second space 68 are connected directly, without passing through another device (suction device or pressurization device). Therefore, the negative pressure is applied to the suction space 66 by the suction device 74, and the positive pressure is applied to the drying space 68 through the liquid collection container (sealed container) 78. The operation start and halt timings of the suction device 74 are the same as those of the solvent absorbing device shown in FIG. 6.

According to the present embodiment, by applying the negative pressure to the first space 66 while applying the positive pressure to the second space 68, it is possible to promote the collection of the excess solvent by the absorbing body 62 and to dry the absorbing body 62 through the first and second opening sections 70 and 72.

In particular, the solvent absorbing device shown in FIG. 8 can be achieved by using the single suction device 74, and therefore it is possible to achieve cost reduction and size reduction (space saving).

Fourth Embodiment

Next, a solvent absorbing device according to the fourth embodiment of the present invention is described. Below, the parts common with the above-described embodiments are not explained further, and the following description centers on the characteristic features of the fourth embodiment.

FIG. 9 is a schematic drawing showing the composition of the solvent absorbing device according to the fourth embodiment. In FIG. 9, the parts common or similar with those in FIG. 8 are denoted with the same reference numerals.

The solvent absorbing device shown in FIG. 9 includes a heating device 86, which is arranged between the liquid collection container (sealed container) 78 and the second space 68. Since the air that has been heated by the heating device 86 is supplied to the second space 68, then it is possible to apply the flow of heated air to the absorbing body 62 through the second opening section 72 so as to promote the evaporation of the solvent inside the absorbing body 62. Furthermore, since the heated air can make the viscosity of the solvent inside the absorbing body 62 lowered, then it is possible readily to blow away the solvent toward the outside of the absorbing body 62, and therefore the drying of the absorbing body 62 can be promoted.

The heating device 86 is controlled so as to start heating at the timing that the positive pressure is applied to the second space 68, and to halt heating at the timing that the application of the positive pressure is halted. Moreover, it is desirable that the heating temperature of the heating device 86 is controlled in such a manner that the temperature of the air supplied to the second space 68 is within a range of 40° C. to 80° C. If the absorbing body 62 has poor thermal resistance or the solvent 58 is liable to react with heat, then a desirable mode is one where a temperature sensor is arranged in the second space 68, for instance, and the heating device 86 is controlled on the basis of the temperature measured with this temperature sensor, so as to set the air that is supplied to the second space 68 to an optimum temperature. The operation start and halt timings of the suction device 74 are the same as those of the second embodiment.

FIG. 10 is a schematic drawing showing another composition of the solvent absorbing device according to the fourth embodiment. In FIG. 10, the parts common or similar with those in FIG. 9 are denoted with the same reference numerals.

In the solvent absorbing device shown in FIG. 10, the heating device 86 is arranged in the second space 68. In this case, compared to the solvent absorbing device shown in FIG. 9, the air in the second space 68 can be controlled more readily to an optimum temperature and the heating efficiency is improved.

FIG. 11 is a schematic drawing showing yet another composition of the solvent absorbing device according to the fourth embodiment. In FIG. 11, the parts common or similar with those in FIG. 9 are denoted with the same reference numerals.

In the solvent absorbing device shown in FIG. 11, the heating device 86 is arranged in the second space 68, and the pressurization device 82 is connected to the second space 68. Moreover, the liquid collection container 78 is the non-sealed container, which has the air connection hole 78 a. The positive pressure is applied to the second space 68 by the pressurization device 82, and the air thereby supplied to the second space 68 is heated by the heating device 86.

According to the present embodiment, as well as obtaining similar beneficial effects to those of the third embodiment, it is also possible to promote the evaporation of the solvent inside the absorbing body 62 through the second opening section 72, by means of the heating device 86, and furthermore, since the viscosity of the solvent inside the absorbing body 62 can be lowered, then the solvent can be blown out more readily to the outer side of the absorbing body 62. Thus, the drying of the absorbing body 62 can be promoted more readily.

Fifth Embodiment

Next, a solvent absorbing device according to the fifth embodiment of the present invention is described. Below, the parts common with the above-described embodiments are not explained further, and the following description centers on the characteristic features of the fifth embodiment.

FIG. 12 is a schematic drawing showing the composition of the solvent absorbing device according to the fifth embodiment. In FIG. 12, the parts common or similar with those in FIG. 4 are denoted with the same reference numerals.

The solvent absorbing device shown in FIG. 12 is provided with the solvent removing roller 50 constituted of the hollow open roller 60 in which the inner side of the cylindrical member is divided into three spaces, the first and second spaces 66 and 68 and a third space 90, and in which three opening sections, the first and second spaces 70 and 72 and a third opening section 92, are respectively formed in the first, second and third spaces 66, 68 and 90 so as to pass from the outer surface of the cylindrical member to the inner surface thereof. The cylindrical absorbing body (porous body) 62 is arranged over the outer surface of the hollow open roller 60, and is rotatable relatively with respect to the hollow open roller 60. Three suction devices, the first and second suction devices 74 and 76 and a third suction device 94, are connected respectively to the first, second and third spaces 66, 68 and 90. The suction devices 74, 76 and 94 are connected to the same liquid collection container (non-sealed container) 78.

The first opening section 70 corresponding to the first space 66, the third opening section 92 corresponding to the third space 90, and the opening section 72 corresponding to the second space 68, are disposed in sequence toward the downstream side from the solvent contacting surface of the absorbing body 62, following the direction of rotation of the absorbing body 62. In other words, the third opening section 92 is disposed to the downstream side of the opening section 70, in terms of the direction of rotation of the absorbing body 62, and to the upstream side of the second opening section 72 in terms of the direction of rotation of the absorbing body 62.

A liquid deposition device 96 is provided at a position opposite to the third opening section 92 through the absorbing body 62. The liquid deposition device 96 deposits a prescribed liquid (for example, water or cleaning liquid) onto the surface of the absorbing body 62 placed over the third opening section 92. There are no particular restrictions on the liquid deposition method used by the liquid deposition device 96, and it is possible to use various methods, such as spraying, dripping, spreading, or the like.

Due to the negative pressure applied to the absorbing body 62 by the third suction device 94 through the third space 90 and the third opening section 92, the liquid deposited on the surface of the absorbing body 62 by the liquid deposition device 96 is absorbed efficiently in a short period of time into the absorbing body 62, and the excess solvent of the ink having been absorbed in the absorbing body 62 and the liquid deposited by the liquid deposition device 96 on the absorbing body 62 are collected into the third space 90 though the third opening section 92. Consequently, the viscosity of the solvent having been absorbed in the absorbing body 62 is lowered, and the absorbing body 62 is dried on the downstream side in terms of the direction of rotation of the absorbing body. Furthermore, if a cleaning liquid is deposited on the absorbing body 62 by the liquid deposition device 96, then foreign material adhering to the absorbing body 62 can be collected and blockages can be prevented. In general, the solvent of the ink includes a high-boiling-point solvent such as glycerin. The high-boiling-point solvent has a high viscosity compared to water and if the high-boiling-point solvent contained in the absorbing body 62 dries directly in the absorbing body 62 then the viscosity rises further and there is a risk that blockages may occur. On the other hand, by depositing the liquid on the surface of the absorbing body 62 by means of the liquid deposition device 96, while applying the negative pressure to the third space 90 by means of the third suction device 94 as described above, it is possible to reduce the amount of high-boiling-point solvent remaining in the absorbing body 62 by lowering the viscosity of the solvent in the absorbing body 62 while it is collected, and therefore the prescribed absorptive properties of the absorbing body 62 can be maintained.

Next, the operation start and halt timings of the third suction device 94 according to the present embodiment are described.

With regard to the operation start timing of the third suction device 94, for example, soil of the absorbing body 62 is determined by using a detector (not shown) such as a reflective optical sensor, or the like, and when the soil has become heavier than a prescribed threshold, the operation of the third suction device 94 is started and the liquid is deposited by the liquid deposition device 96. With regard to the operation halt timing of the third suction device 94, the soil is determined by the detector at regular sampling timings, and the operation of the third suction device 94 is halted when the soil has not exceeded the prescribed threshold for a number of determination operations corresponding to one revolution of the absorbing body 62. For example, it is desirable that the sampling timing interval is set to 1/10 to 1/2 of the period taken for the absorbing body 62 to perform one revolution.

Moreover, as a further example, the amount of solvent or the recording time is calculated from the image data, the total solvent volume or recording time is determined accordingly, and when this total becomes greater than a prescribed threshold, then the operation of the third suction device 94 is started and the liquid is deposited by the liquid deposition device 96. As regards the timing at which the operation of the third suction device 94 is halted, this timing is set either to the time at which the non-permeable medium 52 is halted, or after the liquid deposition has been performed for a prescribed time period. At the halt timing, the total of the solvent volume or the recording time is reset and when the liquid deposition is next performed, the calculation process is repeated again.

The operation start and halt timings of the first and second suction devices 74 and 76 are the same as those of the solvent suction device shown in FIG. 4, and therefore detailed description thereof is omitted here.

According to the present embodiment, since the viscosity of the solvent inside the absorbing body 62 is lowered by the liquid deposited by the liquid deposition device 96, while the excess solvent is collected by the absorbing body 62 and subsequent drying of the absorbing body 62 is carried out, then it is possible to reduce the amount of high-boiling-point solvent remaining in the absorbing body 62. Consequently, since the solvent collection, the lowering of the solvent viscosity and the drying are repeated successively in the absorbing body 62 rotatable relatively with respect to the open hollow roller 60, then there is no decline in the absorptive properties of the absorbing body 62, and the collection of the excess solvent can be carried out continuously and reliably, while maintaining desired absorption performance.

Sixth Embodiment

Next, a solvent absorbing device according to the sixth embodiment of the present invention is described. Below, the parts common with the above-described embodiments are not explained further, and the following description centers on the characteristic features of the sixth embodiment.

FIG. 13 is a schematic drawing showing the composition of the solvent absorbing device according to the sixth embodiment. In FIG. 13, the parts common or similar with those in FIG. 4 are denoted with the same reference numerals.

The solvent absorbing device shown in FIG. 13 has a cylindrical liquid storage section 98 formed in the central portion of the inner side of the hollow open roller 60. The inlets of the first and second suction devices 74 and 76 are respectively connected to the first and second spaces 66 and 68, and the outlets of the first and second suction devices 74 and 76 are connected to the liquid storage section 98.

The excess solvent collected by the suction devices 74 and 76 is accumulated in the liquid storage section 98. When the absorbing body 62 is replaced with a new one, due to deterioration, it is possible simultaneously to discard the excess solvent accumulated in the liquid storage section 98, and therefore the associated maintenance tasks can be simplified. Furthermore, since there is no need to provide a separate liquid collection container, it is also possible to save space.

The operation start and halt timings of the suction devices 74 and 76 are the same as those of the solvent absorbing device shown in FIG. 4.

As described above, according to the solvent absorbing device of the present invention, it is possible to promote the collection of the excess solvent by means of the absorbing body 62 through the first opening section 70, due to the negative pressure applied to the first space 66, and it is also possible to carry out drying of the absorbing body 62 through the second opening section 72, due to the prescribed pressure (negative pressure or positive pressure) applied to the second space 68, to the downstream side in the direction of rotation of the absorbing body 62. In other words, in the absorbing body 62 rotating over the outer side of the hollow open roller 60, the solvent collection and the drying are repeated alternately, and consequently there is no decline in the absorptive properties of the absorbing body 62 and it is possible to collect the excess solvent continuously in a reliable manner, while maintaining a prescribed absorption performance.

In the above-described embodiments, the interior of the hollow open roller 60 is divided into two or three spaces, but in implementing the present invention, it may be divided into four or more spaces. For example, a mode is possible in which each of the first and second spaces 66 and 68 is divided into a plurality of spaces (small chambers), and a prescribed pressure is applied to each of these small chambers independently. According to this mode, it is possible to optimize the solvent collection and the drying, in accordance with the size of the recorded image.

It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but on the contrary, the invention is to cover all modifications, alternate constructions and equivalents falling within the spirit and scope of the invention as expressed in the appended claims. 

1. A solvent absorbing device, comprising: a hollow open roller composed of a cylindrical member of which inner side is divided into at least a first space and a second space in such a manner that a cross-section of the cylindrical member in a plane perpendicular to an axial direction of the cylindrical member is divided into a plurality of regions, the cylindrical member having a first opening section and a second opening section passing from an outer surface of the cylindrical member to an inner surface of the cylindrical member and opening respectively to the first space and the second space; a cylindrical absorbing body which is arranged over the outer surface of the cylindrical member and is rotatable in a rotational direction relatively to the hollow open roller; and a pressure application device which applies a negative pressure to the first space of the hollow open roller, and applies a prescribed pressure to the second space of the hollow open roller, wherein the first and second opening sections are disposed other than a position facing a portion of a surface of the absorbing body making in contact with solvent, and the first opening section is disposed on an upstream side of the second opening section in terms of the rotational direction of the absorbing body.
 2. The solvent absorbing device as defined in claim 1, wherein the pressure application device applies a negative pressure to the second space.
 3. The solvent absorbing device as defined in claim 1, wherein the pressure application device applies a positive pressure to the second space.
 4. The solvent absorbing device as defined in claim 3, further comprising a heating device which heats air to be supplied to the second space.
 5. The solvent absorbing device as defied in claim 1, wherein: the cylindrical member further has a third space in the inner side and a third opening section opening to the third space; the third opening section is disposed on a downstream side of the first opening section and the upstream side of the second opening section in terms of the rotational direction of the absorbing body; and the solvent absorbing device further comprises a liquid deposition device which deposits a prescribed liquid onto the surface of the absorbing body and is arranged at a position facing the third opening section through the absorbing body.
 6. The solvent absorbing device as defined in claim 1, wherein the cylindrical member further has a liquid storage section in the inner side, collected excess solvent being accumulated in the liquid storage section.
 7. An image forming apparatus comprising the solvent absorbing device as defined in claim
 1. 